# Questions tagged [orbital-elements]

Orbital elements are a set of parameters that uniquely identify a specific orbit.

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### Is it possible to determine the classical orbital elements for an Elliptic Repeating SSO?

As in the title, it is possible to have a repeatable Sun-synchronous orbit but with an elliptic eccentricity? If yes, which equations I have to consider to determine its classical orbital elements?
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### Plot ellipse using elements from TLE

I am trying to draw an ellipse as satellite orbit in three.js, It has an EllipseCurve class which takes these inputs and draws an ellipse around center. EllipseCurve( aX : Float, aY : Float, xRadius : ...
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### Relationship between osculating eccentricity and Brouwer-Lyddane short eccentricity

I was under the impression that the mean elements are given by taking the average over an orbital period of the satellite, i.e.: $e_{mean}(t) = \int_{t}^{t+T(t)}e_{osc}(t')dt'[0.367in]$ where $T(t)$ ...
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### Is electric propulsion feasible for human spaceflight?

I have been reading a lot about electric propulsion and was wondering if it would be feasible for human spaceflight. It is really efficient but it takes a while to get to the desired speed. Would it ...
1 vote
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### How do I correctly convert State Vectors to Orbital Elements to State Vectors at t (sec since epoch) in 2D?

I am following Rene Schwarz' formulas and I've verified my calculations work using the converter by Tony Dunn. State Vectors to Orbital Elements Orbital Elements to State Vectors Convert between ...
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### Predicting Satellite Flyover Calculations by Hand

Recently I used transit-finder.com to get a really cool picture of the ISS transiting the sun. The prediction from the website was spot-on. Since then I'm absolutely fascinated by how the prediction ...
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### Is there a parameter that describes the angle between the spacecraft's position and the sun angle or direction of the Earth's motion?

I am trying to design an Earth flyby for gravity assist in GMAT, and I know from theory that the spacecraft should pass in front of a planet with regard to its heliocentric direction of motion in ...
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### What maneuvers could be useful to move between two sun synchronous orbits with different times?

Consider two sun-synchronous orbits with similar orbital elements, except for their times. For example 8h and 9h orbits. Their semi-major axes (a), inclinations (i), and eccentricities (e) are the ...
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### Why does a launch due south (180° azimuth) not translate into a polar orbit from Vandenberg?

I found this image showing the allowable launch azimuths for Vandenberg AFB and I was wondering why a 180° launch azimuth doesn't match a 90° inclination orbit. This led me to question the equation ...
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### Different/better ways to calculate the shadow region passage of the satellite and the effect of orbital elements, other than shadow cone technique?

The NASA Technical Publication Method for the calculation of spacecraft umbra and penumbra shadow terminator points; TP-3547 describes the following: A method for calculating orbital shadow ...
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### Why is the eccentricity vector used to describe near-circular orbits?

When dealing with near-circular orbits I've seen the usage of the eccentricity vector defined as $$(e_x,e_y) = (e\cos\omega, e\sin\omega)$$ I've seen this in Schaubs' "Analytical mechanics of ...
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### What type of galactic orbit will the Voyager probes have?

I know that they will eventually get close (within 10,000 light years) of our solar system, but will the orbit be circular or elliptical, around how much eccentricity, what would be a reasonable ...
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### Compute orbital parameters from transverse and radial velocity at a given distance from the focus

I've been pulling my hair on this problem for a couple of days now, researched a lot but have not been able to find results. Basically I'm writing a program capable of drawing a transfer orbit between ...
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### Obtaining orbital state vectors given two position vectors and an eccentricity

I was looking into the dynamics of basic 2-system orbits, and I came across a PDF (attached below) showing how to calculate orbital elements given a position and velocity vector. This led me to the ...
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### Is there a low Earth orbit with a 24-hour day night cycle?

Are there any possible low-Earth orbits that use precession to match Earth's day/night cycle? So like SSO, but specifically aimed to achieve a 24hr day/night in LEO. If so, what would its parameters ...
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### Osculating oscillations! What makes Akatsuki's eccentricity and inclination about Venus vary periodically?

Watching this animated GIF of Akatsuky's orbit I noticed that it seems to "walk" around Venus. Some orbital elements oscillate ~3-4 times a year, others drift and then slowly "step up ...
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### Why are there six orbital elements?

I have knew for a long time that there were six orbital elements but I never knew why it was six and not any other arbitrary number? Does it have do with the fact that there is 3 components for both ...
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### How to sort orbital positions in the order of following by spacecraft?

I have an orbiting spacecraft which keplerian elements is known. Also, I have a random-ordered list of true anomalies that represents spacecraft's positions on that orbit. How to sort this list to get ...
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### How to calculate the Lagrangian points positions?

I have two bodies, one rotates around another on orbit. For i.e. Earth and Sun or Moon and Earth. If we know masses, velocity, distance and keplerian elements of orbit, how can we find the positions ...
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### Differences between numerical propagators

I am a trainee who is working on a numeric orbital propagator developed in the company. I can't show you the code but I can tell you that the propagator was developed to work in Simulink. My job was ...
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### How to calculate time needed for spacecraft to travel a given number of meters in elliptical orbit or hyperbolic trajectory?

We have elliptical orbit and spacecraft travelling it. I need a formula to calculate a time needed for spacecraft to travel given amount of meters starting from it's current position. Keplerian ...
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### Is it possible to detect if orbits intersect or not and positions where they intersect if you know Keplerian elements (2D)?

I have two orbits and I know their Keplerian elements. Is it possible to find positions where two orbits are crossing if those positions exist? Is it possible to do it if spacecrafts are on orbits of ...
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### How to calculate future true anomaly for hyperbolic trajectory? Did I make a mistake in my calculations?

I'm trying to calculate future spacecraft's position and velocity at time t. I need to calculate the true anomaly at time t for this. I've already made it for the elliptic orbits and it is working ...
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### How to detect the correct sign of the true anomaly for position prediction (clockwise/counterclockwise rotation)?

I calculated spacecraft's keplerian orbital params from position/velocity using this formulas: https://drive.google.com/file/d/11KhEdFboZCPUjfibtjHaDBWtUTNmJxFA/view?usp=sharing Then I can predict ...
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### Wrong position during orbit propagation in Unity

I've been working on an orbital physics module for months now, and have reached a barrier. I have two methods, one to convert from Kepler elements to planet-centric coordinates, and the other to ...
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### How to find eccentric anomaly by mean anomaly?

Wikipedia gives me the equation M = E - e*sinE I have M and need to find E. How to do it?
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### Are 3 points on an orbit enough to determine the shape of it in practice?

In a question about determining orbital elements from two points on an orbit, some discussion arouse regarding how many points are actually necessary, since two is not sufficient. Determining a conic ...
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### Find the Orbital Inclination given all other Elements and a Position on the Ellipse

I'm in a situation where I need to determine an orbit's inclination. At my disposal I have all of the orbit's other Keplerian elements, and I have the vector of a single point on the ellipse. Is ...
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### How would you calculate a Hohmann transfer going towards the sun?

If you were going from a lower orbit to a higher orbit such as a Earth-Mars transfer, you would use the periapsis of the transfer orbit in the vis-viva equation to calculate the delta V. But if you ...
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### Right Ascension of the Ascending Node (RAAN) Drift and Correction

This one can be a very short and easy question, but I wanna know the proper answer of them.. Few days ago I got a questions like: "What kind of perturbation(s) can cause drift on RAAN value of a ...
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### How is it possible that the windows on the ISS mostly face Earth only? [duplicate]

In this article astronaut Clayton C. Anderson states that on the ISS the windows "mosty face Earth, which means that it is only possible to see the stars at the very edges of the windows, and ...
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### Calculating TLE, or satellite orbit elements based on angle information (RA and Dec) at multiple epochs

new here. I am trying to 'determine' orbital elements of a given satellite. Based on TLE from space-track, or CelesTrak, I observed several satellites resulting in 10 to 20 RA and Dec pairs for each ...
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### Obtaining position of GPS and GLONASS satellites from RINEX navigation files

I am currently trying to understand the best way to use the available information in RINEX navigation files for GPS and GLONASS satellites. My main goal currently is to calculate the position at epoch ...
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### How would you convert keplerian orbital elments into cartesain vectors with quaternions?

Coverting the keplerian elements to cartesain vectors ( posistion and velocity) is relatievly simple by using rotation matrices show in the document here: https://downloads.rene-schwarz.com/download/...
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### what range of orbital inclinations will be needed to reach Mars from the Boca Chica launch site?

When SpaceX fly missions out of Boca Chica in South Texas to Mars what orbital inclination will the launch need to be to put the spacecraft on to best transfer orbit to Mars? And will this vary with ...
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### Finding the new true anomaly after performing a maneuver

Given a standard set of orbital elements (angular momentum, semi-major axis, eccentricity, inclination, longitude of the ascending node, argument of periapsis, and true anomaly), and a global time ...
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### Rotation matrix / coordinate transformation of maneuver parameters from Prograde, Normal, Radial to Cartesian XYZ?

Say I have a state vector and Keplerian elements of an orbiting spacecraft: Position = [x, y, z] Velocity = [vx, vy, vz] Elements = [a, e, i, $\omega$, $\Omega$, $\nu$] And I have the maneuver I ...
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### How can I calculate the future position of a satellite orbiting a central body as a function of time using known orbital elements?

Given the position and velocity vectors at one point in an orbit, one can calculate the keplerian elements and thus graph the subsequent orbital path as a circle/ellipse/parabola/hyperbola depending ...
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### Is there a (low-thrust) thrusting strategy to change a single orbital element alone?

In literature, I have found the optimal thrusting directions (in terms of pitch and yaw) for maximizing changes in each orbital element. These optimal changes, while maximizing one element, have an ...
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### What's the lowest periapsis of a successful orbit around the Moon? [duplicate]

What's the lowest periapsis of a successful orbit around the Moon ever made by a moon-orbiting spacecraft? Theoretically, Moon-orbiters can go as low as a foot above the surface due to the lack of an ...
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### Is Vallado's Revisiting Spacetrack Report #3 still relevant today?

The title pretty much sums it up. I am reading David A. Vallado's Revisiting Spacetrack Report #3, which was published in 2006 and includes source code for the SGP model series. I was wondering, is ...
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